Former British spy Christopher Steele issued a memo in November 2016 reporting that the Kremlin had used its influence to block the nomination of Mitt Romney to secretary of state, Jane Mayer reported for New York Magazine.

Steele, author of the infamous dossier on President Donald Trump, wrote the memo after his work with Fusion GPS had ended. And Steele had just one source — a "senior Russian official," Mayer reported.

Further, Mayer reports that Steele is believed to have shared the sourcing of that memo — and all the rest of the memos that comprised the Trump dossier — with special counsel Robert Mueller.

"The memo said that the Kremlin, through unspecified channels, had asked Trump to appoint someone who would be prepared to lift Ukraine-related sanctions, and who would cooperate on security issues of interest to Russia, such as the conflict in Syria," Mayer wrote.

Trump ultimately settled on Rex Tillerson after meeting with Romney at Trump Tower and dining with the former presidential candidate and fierce critic of Trump's during election season.

Romney had called Russia the single greatest threat to the U.S. during his 2012 presidential bid.

Mayer's Kremlin-Romney report is part of the 15,000-word wide-ranging piece she wrote for the March issue of New York Magazine detailing the origins of Steele and timeline of his work in piecing together the dossier.